Odds of Getting In
Becoming a paid locksmith is not at all difficult to do. You either need to attend classes at a community college (or go to a trade school), or you can become a locksmith's apprentice. Apprenticing means you'll be getting hands-on training from someone already in the biz.
That means you'll have to get them to teach you in the first place, so you'll have to prove you're worthy of their training, young Padawan. The upside is you don't have to pay anything for this training; the downside is, you're basically free labor.
The point is that someone with knowledge and experience passes that knowledge and experience on to you, so you don't show up at your first locked car job and end up totaling your customer's ride.